1. Field of the Invention
The present invention relates to a manufacturing method of a power metal-oxide-semiconductor field-effect transistor (MOSFET); in particular, to a manufacturing method of a trench power MOSFET.
2. Description of Related Art
Power metal-oxide-semiconductor field-effect transistors (Power MOSFET) are widely implemented in the switching devices of electric devices, such as power supply, rectifier or low voltage motor controllers and the like. The current power MOSFET is designed to have a vertical structure to improve the packing density. The power MOSFET having trench gate structure not only results in higher packing density, but also has lower on-state resistance. One of the advantages of the trench power MOSFET is that it is capable of controlling the operation of devices with low-power consumption.
The working loss of power MOSFET is categorized into a switching loss and a conducting loss. In addition, an intrinsic gate-to-drain capacitance (Cgd) is one of the important parameters affecting the switching loss. When the intrinsic gate-to-drain capacitance is too high, the switching loss increases, which may limit the switching speed of the power trench MOSFET and may lead to the trench power MOSFET being unfavorable to be implemented in high frequency circuits.